Watch as the electricity kills the headcrabs, then walk up to the vent shaft. Second is the small vent near the live wire. If you even attempt to walk past the wire, you will get fried. You need to turn off the power before you head this way. The first is the broken ceiling tile and the live electric wire that is hanging down. There are several things to take notice of here. Take the battery and the medkit that are nearby.
When the elevator reaches the ground floor, the doors will open.
Go into the room with the danger sign and press the switch inside to disable the power.
